Air heaters of the rotary regenerative type includes a rotor which is mounted for rotation either about a horizontal axis or a vertical axis. The rotor is made up of a plurality of metal plates stacked tightly within a plurality of sector-shaped baskets. The air heater normally is used for extracting heat from exhaust gases leaving the furnace of a steam generaor, and transferring this heat to a stream of air used to support combustion of fuel within the furnace.
During operation, particularly when the axis of the rotor is positioned horizontally, problems are encountered due to corrosion and breakage of some of the heating plates, so that they become somewhat loose within the baskets. The plates then rub and slide against one another causing abrasive wear, which substantially reduces the life of such plates. One manner of solving this problem is to drive metal wedges between the plates within the basket to thereby tighten them. This is done during scheduled maintenance shutdowns of a unit.
The wedges add weight to the air heater, and also create unbalance of the rotor about its axis of rotation. Access to the inside of the air heater for permitting the wedges to be driven into place by an operator is also a costly and time consuming procedure, requiring partial disassembly of the air heater.